Typically, cable ties have a strap that can be engaged in a head. The head includes a pawl or another structure that locks the strap in the head. One criterion for cable quality is its tensile strength, defined as the amount of force needed to cause the cable tie to fail once it has been properly engaged around a structure. The load which a cable tie can handle is dictated by the cable tie's tensile strength.
It is sometimes desirable to remove a cable tie after it has been installed. However, as cable ties need to have a sufficient tensile strength for the task, by definition they are not designed to be easily removed. Most times, cable ties are removed by cutting the strap. This presents several problems, however. For one, an appropriate cutting tool is required. Further, the tool must be forced between the strap and the structure to which it is engaged, which can be difficult to accomplish. Also, as the straps are made of a tough material (typically a tough nylon material), they are difficult to cut.
Tearaway or breakaway cable ties have a narrowed region in the strap that can more easily be torn or broken by the user. However, this inherently weakens the strap, decreasing its tensile strength and thus its utility.